Drone delivery allows low cost delivery of small light items. A delivery item may be attached to a drone that is programmed to fly to a delivery site. Drones have the advantage of avoiding traffic, and generally require less energy for a delivery than is require to deliver a package by a truck. A drone flight path can be scheduled to avoid heavily populated areas, restricted air space, and obstacles such as buildings or hills.
While drones offer promise for quick delivery in less populated areas, there are significant challenges for drones in heavily populated areas. In such places, a malfunction of a drone can be a safety hazard. Flight restrictions due to inclement weather of restricted air space can also limit the effectiveness of drones. Also, the energy required for flying puts limits on payload capacity, range and flight time of drones. When drones are battery powered, recharging or changing batteries can be inconvenient and/or time consuming.